Consumers have been treating amino acid based substrates for years. Such treatments have included the waterproofing or coloring of textiles, the sunscreening of skin, the coloring, conditioning, and styling of hair, the dentifrice treatment of teeth, and more. It is well known that if such treatments can be done by a safe covalent attachment to the substrate, that the treatment will be much more long lasting. Therefore, several reactive chemistries have been developed to provide covalent attachment to amino acid based substrates such as hair. Historically, these technologies, based on covalent attachment of cosmetic actives, have primarily relied upon electrophilic (electron accepting) and nucleophilic (electron donating) reactive groups or “hooks”. More recently, a Protected Thiols “hook” technology for the covalent attachment of cosmetic actives to amino acid substrates has been proposed.
It is highly desirable to formulate consumer products as aqueous solutions or aqueous emulsions for a number of consumer preferred attributes, e.g., ease of rinsing, aesthetic feel, less coating of bathroom tiles, environmental concerns, etc. However, attaining such aqueous compositions is problematic in the delivery of technologies for the covalent attachment of cosmetic actives to amino acid based substrates. The reactive groups or “hook” moieties which are reactive towards amino acid residues in hair protein are also reactive towards electron rich ingredients that are employed in the formulation of consumer products to deliver these actives, including water and even atmospheric oxygen. This leads to pre-mature decomposition of the hooks of covalent reactive compounds, referred to herein as reactive agents, over the shelf life of the product which severely or completely mitigates reactive efficacy with a substrate upon usage by the consumer.
While the prior art delivery systems have addressed some of the problems of achieving covalent attachment of cosmetic actives to amino acid based substrates, they have not addressed the problems to the extent of or in the manner of the present invention, and there is a continuing need for additional improved delivery system approaches that will enable the formulation and delivery of reactive agents to amino acid based substrates from an aqueous composition that is chemically shelf stable.